The present invention relates generally to a class of antimicrobials useful in pharmaceutical and cosmetic products. In particular, the present invention relates to polymeric quaternary ammonium compounds which are useful as disinfectants and preservatives for ophthalmic, pharmaceutical and contact lens care products.
Polymeric quaternary ammonium compounds as a class have been known for many years. British Patent No. 536,017 (Aug. 30, 1941), assigned to E. I. DuPont de Nemours (the "DuPont Patent"), discloses linear polymeric quaternary ammonium compounds and methods for their preparation. The method of the DuPont Patent may be generically described as a condensation reaction between a lower alkyl dihalide and a difunctional ditertiary amine. Contemplated uses for the compounds of the DuPont Patent include their use in photographic processing, to treat leather, as mold inhibitors and pesticides, and as modifying agents. There is no mention of use of these compounds as disinfectants or preservatives in pharmaceutical products.
U.S. Pat. Nos. 3,931,319 (Jan. 6, 1976), 4,001,432 (Jan. 4, 1977) and 4,012,446 (Mar. 15, 1977), all issued to Green, et al., disclose a group of high molecular weight "capped" linear polymeric quaternary ammonium compounds found to be effective microbiocides (antimicrobials). The Green, et al. compounds are "capped" in the sense that both ends of the chains terminate in quaternary ammonium moieties. In a continuation-in-part application, now U.S. Pat. No. 4,027,020 (May 31, 1977), Green, et al. disclose a process for making randomly capped linear polymeric quaternary ammonium compounds; that is, the polymers produced by the improved process include those with very short chain lengths as well as those having relatively long chain lengths. These compounds were also found to have antimicrobial activity.
U.S. Pat. Nos. 4,407,791 (Oct. 4, 1983) and 4,525,346 (Jun. 25, 1985), both issued to Stark, disclose improved disinfecting solutions for contact lenses, wherein the aqueous solutions contain the Green, et al. polymers including the commercially known Onamer M.RTM.. In addition, U.S. Pat. No. 5,037,647 (Aug. 6, 1991 ), issued to Chowhan et al., disclose aqueous antimicrobial ophthalmic solutions containing Onamer M.RTM. in combination with an anionic complexing agent to prevent or to reduce binding of the polymer to contact lenses.